Large prints are laminated by industrial laminating machines which do not use individual envelopes of laminating material for the prints. Instead the prints are fed through the machine with top and bottom edges overlapping and laminating material is drawn to the continuous line of prints from a supply roll above the line or from supply rolls both above and below the line. Having been laminated the individual prints must then be separated. This is done by tearing the leading print from the line across the overlap between its trailing edge and the leading edge of the next print. The tearing is effected by a pair of rolls downstream of the machine which rotate slightly faster than the rolls which have passed the line of prints through the laminating process. This pair of rolls is slightly “skewed” in relation to the direction of movement of the line to produce a tearing effect. If subjected to shear forces the film or films of laminating material will simply stretch without tearing. However if perforated the film will tear with no difficulty. It has therefore been proposed to indent or pierce the film at the position where two prints overlap. In the case of the film applied on top of the prints this has been effected by a toothed wheel applied to the line of prints at a position downstream of where the film is applied to the prints, a support roller engaging the underside of the prints. The toothed wheel indents or pierces the film near to the side of the line of prints which is first subjected to shear forces by the “skewed” pair of rolls.
It has been proposed simultaneously to laminate the underside of the line of prints from a roll of laminating material disposed near to the bottom of the machine. In this case the indenting or piercing of the film has occurred at the supply roll itself. This means that a substantial length of the film is indented or perforated before it reaches the position in which a print is torn off. This is undesirable because the film may tear before it reaches the position in which it is intended to be torn.
A principal object of the present invention is to provide a solution to this problem.